1. Field of the Invention
The present invention relates to a pixel and a light emitting display using the same, and more particularly to a pixel capable of displaying a uniform image in spite of deviation in processes and a light emitting display using the same.
2. Discussion of Related Technology
Recently, various flat panel displays of advantageously reduced weight and volume compared to cathode ray tubes (CRT) have been developed. Flat panel displays include liquid crystal displays (LCD), field emission displays (FED), plasma display panels (PDP), and light emitting displays.
Among the flat panel displays, the light emitting displays have spontaneous emission devices that emit light by re-combination of electrons and holes to display images. The light emitting displays have high response speed and are driven by low power consumption.
FIG. 1 is a circuit diagram illustrating a pixel of a conventional light emitting display.
Referring to FIG. 1, the pixel 4 of the conventional light emitting display includes a pixel circuit 2 connected to an organic light emitting diode display (OLED), a data line Dm, and a scan line Sn to emit light from the OLED.
The anode electrode of the OLED is connected to the pixel circuit 2 and the cathode electrode of the OLED is connected to a second power source ELVSS. The OLED generates light according to the current supplied by the pixel circuit 2.
The pixel circuit 2 includes a second transistor M2 connected between a first power source ELVDD and the OLED, a first transistor M1 connected among the second transistor M2, the data line Dm, and the scan line Sn, and a storage capacitor C connected between the gate terminal and a first terminal of the second transistor M2.
The gate terminal of the first transistor M1 is connected to the scan line Sn and a first terminal of the first transistor M1 is connected to the data line Dm. The second terminal of the first transistor M1 is connected to one terminal of the storage capacitor C. Here, the first terminal is set as one of a source terminal and a drain terminal and the second terminal is set as the other terminal different from the first terminal. For example, when the first terminal is set as the source terminal, the second terminal is set as the drain terminal. The first transistor M1 is turned on when a scan signal is supplied by the scan line Sn to supply a data signal supplied by the data line Dm to the storage capacitor C. At this time, the voltage corresponding to the data signal is charged in the storage capacitor C.
The gate terminal of the second transistor M2 is connected to one terminal of the storage capacitor C and the first terminal of the second transistor M2 is connected to the other terminal of the storage capacitor C and the first power source ELVDD. The second terminal of the second transistor M2 is connected to the anode electrode of the OLED. The second transistor M2 controls the amount of current that flows from the second power source ELVDD to the OLED corresponding to the voltage value stored in the storage capacitor C. Thusly configured, the OLED generates light with brightness corresponding to the amount of current supplied by the second transistor M2.
However, the above-described conventional pixel 4, does not display images with uniform brightness across various pixels. Actually, the threshold voltage of the second transistor M2 varies with each pixel due to deviation in processing. Therefore, although the same data signal is applied, light with different brightness is generated by the various pixels.